Heating and cooling units

ABSTRACT

A heating and cooling unit comprising a flexible metal band formed in halves connected end-to-end around an object. The band carries a sheathed electric heating element and a metal cooling tube so that the object may be either heated or cooled. The heating element and cooling tube are pressed into direct engagement with the peripheral surface of the object when the bandis positioned around the latter.

O United States Patent 1 [1 11 3,730,262 Drugmand' 5] May 1, 1973 54HEATING AND COOLING UNITS 2,549,569 4/1951 Bradley ..l/30 l Inventor:ester D. Drugmand Pittsburgh, Pa. 2,721,729 10/1955 an Rlper ..l65/64:

[73] Assignee: Emerson Electric Co., Saint Louis, Primary Examinercharles Sukalo Attorney-Michael Williams [22] Filed: I Aug. 6, 1971 57 vABSTRACT PP 169,728 A heating and cooling unit comprising a flexiblemetal band formed in halves connected end-to-end around an object. Theband carries a sheathed electric heating ..165/46, l65/4;,2l;55/64element and a metal cooling tube so that the object 58 8 7/00 y beeither heated or cooled. The heating elemeht mid of Search ..l65/30, 29,48, 64, and cooling tube are pressed into direct engagement /46 169,with the peripheral surface of the object when the bandis positionedaround the-latter. [56] References Cited UNITED'STATES PATENTS 7 Claims,8 Drawing Figures 1,873,838 8/1932 Gebhard ..'.....l65/30- Patented May1, 1973 2 Sheets-Sheet 1 INVENTOR. LE sTER D DRUGMAND Patented May 1,1973 2 Sheets-Sheet 2 INVENTOR. I

3 LEsTER DRUGMAND KRN BY N A TTORNE;

HEATING AND COOLING UNITS BACKGROUND AND SUMMARY The improved structureis particularly suited for the heating and cooling of the plasticizingtube of an extruder for thermoplastics, although it will be appreciatedthat it may have other applications. In extruders for thermoplastics,control of the temperature of the plastic being extruded is importantsince although initially the extruding chamber may require heat tosoften the plastic to proper extrudable condition, consideration must begiven to the heat energy developed as a result of the friction of theplastic particles driven v forwardly by the extruding screw. Thus,unless the temperature of the plasticizing tube is not carefullycontrolled, an excess amount of heat may have an adverse effect on theplastic being extruded.

Heating and cooling arrangements for extruding apparatus are within theprior art but in some cases require adaptation of the extruding tube toaccommodate the same. Band type arrangements have also been proposed butthese, insofar as I am aware, utilized a heat sink structure, likemetallic shoes, between the heating and cooling means and the extrudertube, and therefore were not only more expensive to manufacture but alsoincorporated an objectionable mass which made it difficult to obtainfine control of the heating or cooling cycle.

My invention comprises a flexible metal band which is adapted to beclamped around the plasticizing tube of an extruder the band carrying a'sheathed electric heating element and a metal cooling tube, both ofwhich are presseddirectly against the peripheral surface of theplasticizing tube so that each may quickly influence the temperature ofsuch tube at the required time.

DESCRIPTION OF THE DRAWINGS In the drawings accompanying thisdescription and forming a part of this specification, there is shown,for purpose of illustration, an embodiment which my invention mayassume, and in these drawings:

FIG. 1 is a section taken transversely through the plasticizing tube ofan extruder, my improved construction being shown applied to such tube,

FIG. 2 is a plan view of the construction shown in FIG. 1, theplasticizing tube being omitted,

FIG. 3 is an enlarged, fragmentary sectional view corresponding to theline 3-3 of FIG. 2,

FIG. 4 is an enlarged, fragmentary sectional view corresponding to theline 4-,-4 of FIG. 1,

FIGS. 5 and 6 are side views of the cooling and heating members,respectively,

'FIG. 7 is aplan view of the members of FIGS. 5 and 6, showing theirnested relationship, and

FIG. 8 is a fragmentary plan view ofa detail.

DESCRIPTION OF THE PREFERRED EMBODIMENT Although the invention will beparticularly described in connection with the heating and cooling of theplasticizing tube of an extruder, it will be appreciated that it may beemployed in any other application where heating or cooling is to beapplied to the periphery of an object, particularly one round incross-section.

The disclosed embodiment comprises a v flexible metal band 10 which isadapted to be clamped. around a not shown since they form no part of myinvention, but

in conventional construction plasticmaterial to be extruded isintroduced into a hopper at one end of the tube 11 and is forcedtherethrough by a feed screw. to an extruding nozzle at the other end ofthe tube.

In order that the material to be extruded is heated to proper extrudingtemperature, one or more of the units of my invention may be applied tothe plasticizing tube 1 1, such devices also embodying cooling means sothat in the event the plastic material in the tube becomes too hot,heating may be interrupted and cooling immediately applied.

In the disclosed embodiment, the band 10 is formed in halves l4 and 15,which may be identical, as shown. Each band half has a transverse loop16 at its end, such loop being formed by rolling over an end of the bandand spot welding the extremity to the band half at 17. Tensioning means18 may be disposed between adjoin ing loops andin the disclosedembodiment such tensioning means is disposed between each set ofadjoining loops, although one set may merely be connected by a hingejoint.

With particular reference to FIG. 3, the tensioning means 18 comprises ashort rod 19 confined within each of the adjoining loops 16, each rodhaving a transverse opening to pass the shank 20 of an elongated bolt.Each loop 16 is slotted, as seen at 21, to provide clearance for certainparts of the tensioning means.

The head 22 of the bolt seats against the peripher-yof one rod 19 (theupper one seen in FIG; 3) and a washer 23 bears against the periphery ofthe lower rod 19. A

' coil spring 24 is disposed between the washer 23 and a spaced washer25, and a nut 26 is threaded on the end of the bolt shank to adjust thepressure of the spring. A sleeve 27 is disposed around the bolt shankand is of a length to prevent the nut 26 to be drawn up an amount tobottom the convolutions of the spring upon each other. Therefore, acertain amount of spring action is always present. In some cases theupper rod 19 (FIG. 3) and the bolt shank may be formed as an integral T-shaped unit, thus eliminating the need for the head 22 and preventingthe bolt from dropping before the nut 26 is applied when the tensioningdevice is disposed in the reverse position shown at the right hand sideof the band in FIG. 1. 1 3

To assemble the band 10 on the tube 11, the nut 26 of one tensioningmeans may be loosely applied so that the band halves may be sufficientlyopened around the pivot provided by the one tensioning means totransversely clear the tube 11, and then the band halves are closed andthe other tensioning means 18 connected to the band halves. The nuts 26may thereafter be adjusted to establish proper clamping force of theband.

My invention comprises a sheathed electric heating element and a metalcooling tube carried by the band to be pressed directlyagainst theperipheral surface of the plasticizing tube 11 and, in the disclosedembodi- 30d, 30d. Likewise, each cooling tube 31 has a pair of legs 31a,31b, joined by a bight 31c, and also has terminal portions 31d, 31d.Each set comprising a heating element and a cooling tube is nested,asseen in FIG. 7, and preferably the spacing between the legs 31a, 31b, ofthe cooling tube is greater than the spacing between the legs 30a, 30bof the heating element so that the latter legs lie between the former,with the bight 31c permitting the terminal portions 30d, 30d to passtherethrough.

The electric heating elements 30 may be formed in accordance withconventional practice, such as shown in U.S. Pat. No. 2,428,899, issuedto Edwin L. Wiegand. As disclosed in said patent, a coiled resistancewire is disposed within a straight metal sheath and granular refractorymaterial insulates the resistance wire from the sheath. Terminal pinsare connected to opposite ends of the resistance wire and extend fromopposite ends of the sheath. The metal sheath is side-pressed totriangular cross-section and the element may then be bent to the sickleshape shown in FIG. 5, so that its arcuate portion approximatelycorresponds to the periphery of the plasticizing tube 1 1.

FIG. 4 illustrates the cross-sectional shape of the electric heatingelement and as seen the sheath is triangular with a flat surface 30eadapted to be pressed directly against the peripheral surface of theplasticizing tube 11 for increased thermal transfer. The apex 30fdirectly opposite the flat surface bears against the inner surface ofthe band to provide a minimum of thermal conduction to the latter.Instead of the triangular shaped described, the round sheath-may besidepressed to provide a flat surface (for engagement with theplasticizing tube) with the remainder of the crosssection round, asshown in U.S. Pat. No. 2,328,113, issued to W. R..Tuttle et al.

The heating elements 30, 30 are connected to respective band halves 14,15 in any suitable manner, and as herein disclosed two small metalU-shaped clips 35,35 are welded to the apex 30f and extend through velongated openings 36, 36 in the band half. A wire 37 is passed throughthe clips 35 exteriorly of the band and has its ends bent over as seenat 38. It will be appreciated that this connection provides for relativemovement between the heating element and the band to accommodate forexpansion and contraction.

The terminal portions 30d, 30d of each heating element extend throughthe space between adjoining band loops 16, 16 (those loop at the lefthand of the band as seen in FIG. 1) and straddle the tensioning boltshank 20, and a jumper strap 40 may be connected across a pair ofverticallyaligned terminal pins to connect the heating elements inseries relation.

Each cooling tube 31 is also side-pressed to the same cross-section asthe heating elements, and is disposed with a flat surface 3le pressedagainst the periphery of the plasticizing tube 1 l and the band 10pressed against an apex 3lf.'Two small metal U-shaped clips 40,40 arewelded to the apex 31f of each cooling tube and such clips pass throughopenings 41,41 in the band. A wire 42 is passed through aligned clips onthe cooling tube legs, and the ends of the wire are bent over, as shownat 43 in FIG. 8 to hold the cooling tubes assembled with the band. Theopenings 41 are elongated to permit relative movement of the coolingtubes and band for expansion and contraction.

The terminal portions 31d, 31d of each cooling tube extend through thespace between adjoining band loops 16,16 (those loops at the right handof the band as seen' trol energization of the heating elements 30 andflow of cooling water through the tubes 31, depending upon thetemperature of the plastic material being extruded. Since the heatingelements and cooling tubes have flat surfaces pressed directly againstthe periphery of the plasticizing tubes 11, heating and cooling may bequickly effected, and since no further mass (like metal shoes) ininterposed, there is no time lag between the effectiveness of theheating and cooling-cycles.

Asseen in FIGS. 4 and 7, the legs 30a, 30b of each heating element 30are disposed between the legs 31a, 31b of each cooling tube. During theheating cycle, no water flows through the legs of the cooling tube andsuch legs block the side openings of the band and thus provide a shieldto minimize heat loss through the-band side openings and thereforeprovide for concentration of heat on the plasticizing tube 1 l.

Iclaim: 1'. A heating and cooling unit for a tubular object, comprisinga flexible metallic band formed in sections which are connectedend-to-end to clamp around said object, a sheathed electric heatingelement and a metal cooling tube carried by said band, said heatingelement and tube being of arcuate shape to generally conform to thecurvature of the periphery of said object, said heating element and tubebeing pressed directly in contact with the peripheral surface of saidobject when said band is clamped around the latter. 2. A heating andcooling unit for a tubular object, comprising a flexible metallic bandformed in halves which are connected end-to-end to clamp around saidobject, each band half carrying a sheathed electric heating element anda metal cooling tube and said element and tube being of arcuate shape togenerally conform to the curvature of the periphery of said object, eachheating element and cooling tube being pressed directly in contact withthe peripheral surface of said object when said band is clamped aroundthe latter.

3. The construction according to claim 2 wherein each heating elementand cooling tube comprises a pair of side-by-side legs, with the legs ofsaid cooling tubes on opposite sides of the legs of said heating elementto shield against heat loss from the latter outwardly of the 5. Theconstruction according to claim 2 wherein each of said heating elementshas terminal portions extending laterally and outwardly of said bandbetween one pair of adjoining ends for connection to a source ofelectrical energy, and wherein each of said cooling tubes has terminalportions extending laterally and outwardly of said band between theother pair of adjoining ends for connection to a source of coolingfluid.

6. A heating and cooling unit for a tubular object, comprising aflexible metallic band formed in halves which are connected end-to-endto clamp around said object, each band half having loops at oppositeends, tensioning means connected between adjoining loops for drawingsaid band halves around said object, each band half carrying a sheathedelectric heating element and a metal cooling tube, both of hair-pinformation to provide legs in side-by-side relation, and both of arcuateshape to generally conform to the curvature of the periphery of saidobject, each of said elements and said cooling tube having meansextending from an outer peripheral surface for connecting the same to arespective band to permit relative peripheral movement for expansion andcontraction, the inner peripheral surface of each said element and tubebeing flattened and pressed against the peripheral surface of saidobject when said band halves are drawn around the latter, the legs ofeach heating element being disposed between the legs of the respectivecooling tube to be shielded against heat loss when the elements andtubes are pressed against the peripheral surface of said object.

7. A heating and cooling unit for a tubular object, comprising aflexible metallic band adapted to be clamped transversely around saidobject, an elongated sheathed electric heating element and an elongatedmetal cooling tube carried by said band and extending longitudinallyalong the inner surface thereof in sideby-side relation, said heatingelement and said cooling tube being shaped longitudinally to generallyconform to the transverse configuration of said object and being presseddirectly in contact .with the peripheral surface 'of said object whensaid band is clamped around the latter.

1. A heating and cooling unit for a tubular object, comprising aflexible metallic band formed in sections which are connected end-to-endto clamp around said object, a sheathed electric heating element and ametal cooling tube carried by said band, said heating element and tubebeing of arcuate shape to generally conform to the curvature of theperiphery of said object, said heating element and tube being presseddirectly in contact with the peripheral surface of said object when saidband is clamped around the latter.
 2. A heating and cooling unit for atubular object, comprising a flexible metallic band formed in halveswhich are connected end-to-end to clamp around said object, each bandhalf carrying a sheathed electric heating element and a metal coolingtube and said element and tube being of arcuate shape to generallyconform to the curvature of the periphery of said object, each heatingelement and cooling tube being pressed directly in contact with theperipheral surface of said object when said band is clamped around thelatter.
 3. The construction according to claim 2 wherein each heatingelement and cooling tube comprises a pair of side-by-side legs, with thelegs of said cooling tubes on opposite sides of the legs of said heatingelement to shield against heat loss from the latter outwardly of thesides of said band.
 4. The construction according to claim 2 whereinadjoining ends of said band halves are formed with loops, and tensioningmeans are connected between such loops to draw the band around saidobject.
 5. The construction according to claim 2 wherein each of saidheating elements has terminal portions extending laterally and outwardlyof said band between one pair of adjoining ends for connection to asource of electrical energy, and wherein each of said cooling tubes hasterminal portions extending laterally and outwardly of said band betweenthe other pair of adjoining ends for connection to a source of coolingfluid.
 6. A heating and cooling unit for a tubular object, comprising aflexible metallic band formed in halves which are connected end-to-endto clamp around said object, each band half having loops at oppositeends, tensioning means connected between adjoining loops for drawingsaid band halves around said object, each band half carrying a sheathedelectric heating element and a metal cooling tube, both of hair-pinformation to provide legs in side-by-side relation, and both of arcuateshape to generally conform to the curvature of the periphery of saidobject, each of said elements and said cooling tube having meansextending from an outer peripheral surface for connecting the same to arespective band to permit relative peripheral movement for expansion andcontraction, the inner peripheral surface of each said element and tubebeing flattened and pressed against the peripheral surface of saidobject when said band halves are drawn around the latter, the legs ofeach heating element being disposed between the legs of the respectivecooling tube to be shielded against heat loss when the elements andtubes are pressed against the peripheral surface of said object.
 7. Aheating and cooling unit for a tubular object, comprisIng a flexiblemetallic band adapted to be clamped transversely around said object, anelongated sheathed electric heating element and an elongated metalcooling tube carried by said band and extending longitudinally along theinner surface thereof in side-by-side relation, said heating element andsaid cooling tube being shaped longitudinally to generally conform tothe transverse configuration of said object and being pressed directlyin contact with the peripheral surface of said object when said band isclamped around the latter.